System for the automatic establishment of a shortwave telegraphy signal connection

Abstract

A system for the automatic establishment of a shortwave telegraphy signal connection between two transmitter-receiver stations within a frequency range subdivided into several channels. Both stations use their receiver to determine objective measurement values reflecting the transmission conditions over the individual channels. Active and passive channel analysis of the actual quality of the signal transmission is determined at each channel. The transmitter of the calling station is automatically tuned to the channel which corresponds to the best channel quality stored in its memory. A predetermined time after transmitting the call signal, the calling station switches to reception and upon reception of an acknowledgment signal from the counter station automatically begins the message transmitting-and-receiving operation. If after a predetermined time no acknowledgment signal is received, the transmitter automatically switches to the channel stored in its memory with the next best channel quality value.

We claim: 
     
       1. A system for establishing a shortwave telegraphy connection between two transmitter-receiver stations on one of a plurality of channels, comprising: each transmitter-receiver station including a transmitter, a receiver and an antenna, switchable between the transmitter and the receiver for selectively adapting the station to be either a calling station or a receiving station;   each receiver having means to search all of said channels prior to establishing a shortwave telegraphy connection;   testing means at each said station for measuring and evaluting signals received by the receiver of the respective station on each channel to determine objective measurement values of the quality of the signal transmission on each channel, said testing means including means to perform a passive channel analysis on each channel before a shortwave telegraphy connection is established between the two stations including at least measuring and evaluating the strength and jitter of the received signals;   said testing means further including means for performing active channel analysis on the data being transmitted on a particular channel after a shortwave telegraphy connection is established between the two stations on that channel to obtain additional objective measurement values of the signal transmission quality on that channel;   a memory at each said station for storing the objective measurement values as to each channel obtained from said testing means at the respective station of said memory; and   processor means at each station interfaced to said transmitter and receiver, said testing means, and said memory, for controlling the operation of each respective station and for automatically establishing a telegraphy connection between a calling station and a receiving station, said processor means at said calling station comprising means for directing the transmitter of said calling station to transmit a call signal over the channel having the best objective measurement value stored in said memory of said calling station, said processor means at said receiving station comprising means for directing the transmitter of said receiving station to send an acknowledgment signal over the channel of the call signal after receipt of said call signal, and said processor means at said calling station further comprising means for directing the transmitter of said calling station to transmit signals comprised of a succession of bits over the channel of the call signal thereby establishing said telegraphy connection, if the acknowledgment signal is received, and means for directing the transmitter of said calling station to transmit a call signal over a next selected one of said channels if the acknowledgment signal is not received within a predetermined time after the call signal is transmitted;   said processor means at each said station further comprising means to replace the objective measurement values stored in said memory for the channel on which a telegraphy connection has been established, with said additional objective measurement values determined by said testing means through active channel analysis.   
     
     
       2. The system of claim 1 wherein each of said testing means comprises soft decision measuring means for evaluating signals received by the receiver at the station of said testing means. 
     
     
       3. The system of claim 1 wherein each of said testing means comprises means for determining the error rate of bits within signals received by the receiver at the station of said processor means. 
     
     
       4. The system of claim 1 wherein the acknowledgment signal includes a plurality of the objective measurement values from said memory at said receiving station. 
     
     
       5. The system of claim 1 wherein said processor means at said calling station further comprises means to direct said transmitter at said calling station to transmit the objective measurement values stored in said memory of said calling station to said receiving station, and wherein said processor means at said receiving station further comprises means to direct said transmitter at said receiving station to transmit the objective measurement values stored in said memory of said receiving station to said calling station, when said telegraphy connection has been established, and wherein said processor means at each station further comprises means to calculate an optimal sequence of channels for the best transmission between both stations, and means to store said optimal sequence in said memories at each station. 
     
     
       6. The system of claim 1 wherein the call signal includes a plurality of the objective measurement values stored in said memory at said calling station. 
     
     
       7. The system of claim 1 wherein the call signal comprises a series of signal frames, each frame comprising a frame counter word having a sequence of bits to indicate the position of the particular frame within the frame series and a plurality of repeating words, each having a sequence of bits which is repeated in each of the signal frames. 
     
     
       8. The system of claim 7 wherein said processor means at said receiving station includes means for evaluating the frame counter word in the call signal to determine the end of the call signal and means responsive to said evaluating means for switching the antenna of said receiving station into connection with the transmitter of said receiving station at the end of the call signal. 
     
     
       9. The system of claim 8 wherein the repeating words of each frame of the call signal include a synchronizing word, a sender address, and a receiver address. 
     
     
       10. The system of claim 9, wherein said testing means at said receiving station comprises soft decision measuring means for determining confidence values for the bits in received signals. 
     
     
       11. The system of claim 10 wherein said processor means at said receiving station further comprises correlation means for synchronizing the receiver at said receiving station with the synchronizing word in the call signal. 
     
     
       12. The system of claim 10 wherein said processor means at the receiving station further comprises means for summing the confidence values of corresponding bits of the repeating words in successive frames of the call signal. 
     
     
       13. The system of claim 10 wherein the frame counter word is coded so that from any frame counter word the preceding and following frame counter word is determinable through a predefined process of incrementing, decrementing or shifting. 
     
     
       14. The system of claim 1 wherein said processor means at said calling station further comprises means to direct the transmitter at said calling station to transmit the objective measurement values stored in said memory at said calling station to said receiving station as part of the call signal, and wherein said processor at said receiving station further comprises means to update the objective measurement values stored in the memory at said receiving station upon receipt of said call signal by averaging them with the objective measurement values received with said call signal. 
     
     
       15. A method for automatically establishing at a calling station a shortwave telegraphy connection between the calling station and a receiving station on one of a plurality of channels comprising: (a) searching through the channels with a receiver;   (b) performing a passive channel analysis on each channel, said analysis consisting at least of measuring the strength and jitter of the digital signals received by the receiver on each channel to produce objective measurement values for each channel;   (c) storing the objective measurement values in a memory;   (d) tuning a transmitter to the channel having the best objective measurement value;   (e) sending a call signal through the transmitter over the channel to which it is tuned;   (f) waiting a predetermined amount of time for an acknowledgment signal from the receiving station on the channel used for sending the call signal and if no signal is received, tuning the transmitter to a next selected one of said channels and performing steps (e) and (f) until an acknowledgment signal is received;   (g) commencing message transmitting-and-receiving after receiving an acknowledgment signal over the channel used by the call signal and the acknowledgment signal;   (h) performing an active channel analysis on the channel on which message transmitting-and-receiving has been established, said active channel analysis consisting of at least measuring the strength and jitter of the digital signals on said channel to determine additional objective measurement values of the transmission quality of said channel; and   (i) replacing the objective measurement values obtained by passive channel analysis and stored in said memory with the additional objective measurement values obtained by active channel analysis.   
     
     
       16. The method of claim 15 wherein said passive channel analysis includes soft decision measuring of the bits in the received signals. 
     
     
       17. The method of claim 15 wherein said passive channel analysis includes determining the error rate of bits in the received signals. 
     
     
       18. The method of claim 15 wherein the acknowledgment signal includes objective measurement values for each channel stored in said memory at the receiving station. 
     
     
       19. The method of claim 18 further comprising: updating the objective measurement values stored in the memory by averaging them with the objective measurement values received in the acknowledgment signal.   
     
     
       20. The method of claim 15 wherein the call signal comprises a series of signal frames, each frame comprising a frame counter word indicating the position of the particular frame within the frame series. 
     
     
       21. The method of claim 20 wherein each frame of the call signal further comprises a synchronizing word, a sender address and a receiver address. 
     
     
       22. The method of claim 20 wherein each frame of the call signal further comprises a plurality of the objective measurement values stored in said memory at said calling station. 
     
     
       23. A method for automatically establishing a shortwave telegraphy connection at a receiving station with a calling station on one of a plurality of channels comprising: (a) searching through the channels with a receiver;   (b) performing a passive channel analysis on each channel, said analysis consisting at least of measuring the strength and jitter of the digital signals received by the receiver on each channel to produce objective measurement values for each channel;   (c) storing the objective measurement values in a memory;   (d) evaluating the signal received on each channel to determine if it is a call signal;   (e) if the received signal is a call signal, determining the end of the call signal;   (f) switching an antenna from connection with the receiver into connection with a transmitter after the end of the call signal; and   (g) sending an acknowledgment signal over the channel on which the call signal was received;   (h) receiving data signals from said calling station on the channel on which said call signal was received;   (i) performing an active channel analysis on the channel on which said data signals are received, said active channel analysis including at least measuring the strength and jitter of the data signals received to determine additional objective measurement values of the transmission quality of that channel; and   (j) replacing the objective measurement values stored in memory for the channel on which the data signals are being received with the additional objective measurement values for that channel determined by said active channel analysis.   
     
     
       24. The method of claim 23 wherein the acknowledgment signal includes the objective measurement values for each channel stored in said memory at said receiving station. 
     
     
       25. The method of claim 23 wherein said passive channel analysis includes determining the error rate of bits in the received signals. 
     
     
       26. The method of claim 23 wherein said passive channel analysis includes soft decision measuring of a confidence value for the bits in received signals. 
     
     
       27. The method of claim 26 wherein the call signal comprises a series of signal frames, each frame comprising a frame counter word having a sequence of bits to indicate the position of the particular frame within the series of frames and a plurality of repeating words, each having a sequence of bits which is repeated in each of the signal frames. 
     
     
       28. The method of claim 27 wherein the end of the call signal is determined by evaluating the frame counter word. 
     
     
       29. The method of claim 27 wherein the repeating words of each frame of the call signal include a synchronizing word. 
     
     
       30. The method of claim 29 further comprising summing the confidence values of corresponding bits of the repeating words in successive frames of the call signal. 
     
     
       31. The method of claim 30 further comprising: synchronizing the receiver with the synchronizing word of the call signal.   
     
     
       32. The method of claim 27 wherein the frame counter word is coded so that from any frame counter word the preceding and following frame counter word is determinable through a predefined process of incrementing, decrementing or shifting. 
     
     
       33. The method of claim 23 wherein the call signal includes the objective measurement values for each channel stored in memory at said calling station. 
     
     
       34. The method of claim 33 further comprising: updating the objective measurement values stored in memory at said receiving station by averaging them with said objective measurement values received with said call signal.